Noncaking linear secondary alkyl sulfonate and sulfate detergent compositions



United States Patent 14 Claims ABSTRACT OF THE DISCLOSURE Process for suppressing caking tendencies of nonsoap detergents in which the detergent active is an alkali metal or ammonium, secondary alkyl sulfate or alkyl sulfonate in which the alkyl groups have a total of 920 carbon atoms by dispersing in said detergent a small but effective amount of sodium or potassium sulfosuccinate. The amount of anticaking agent incorporated is from 2 to 25%, by weight, based upon said nonsoap detergent. Additionally, the anticaking values of the invention are particularly effective in built particulate solid detergent compositions in which the aforementioned active nonsoap detergent is combined with inorganic sodium salt detergent builders.

The present invention relates to a process for suppressing the caking tendencies of alkyl sulfonate and alkyl sulfate detergents, and to the resulting detergent compositions having improved noncaking properties. More particularly, it relates to the preparation of a particulate solid detergent composition containing alkyl sulfonate or sulfate organic detergent, the alkyl group of the detergent being essentially of straightchain structure, said detergent composition having uniformly dispersed therethrough a minor proportion of an anticaking agent to suppress the caking tendencies of said organic detergent.

For a great number of years the bulk of detergent alkylate used to make the finished detergent composition by conversion to the sulfonic acid, followed by neutraliza tion, has been the monophenyl substituted polypropylene polymers, as described in US. Patents Nos. 2,477,382 and 2,477,383 to Lewis. While these detergent compositions have superior detersive powers, it was recognized early in their development that in the particulate solid forms they were hygroscopic and possessed undesirable caking tendencies. These defects were particularly noticeable in built alkyl benzene sulfonate detergent formulations or compositions useful as household washing powders. To inhibit or prevent the undesirable caking phenomenon, use was made of a number of anticaking agents, particularly satisfactory being sodium benzene sulfonate or sodium toluene sulfonate.

Because of the branched-chain nature of the alkyl polypropylene precursor used in making detergent alkyl-ate, the subsequently sulfonated and neutralized detergent does, not meet the specified requirements of biodegradability. As a result, in order to make available a more biodegradable material, commercial emphasis is being placed on synthetic detergents such as the alkyl sulfates and alkyl sulfonates in which the alkyl group is more linear; i.e., one in which branching is at a minimum and the alkyl or hydrocarbyl group is essentially of straight structure.

Like the branched-chain polypropylene-based detergents, the linear secondary alkyl sulfonates and sulfate possess undesirable caking tendencies. Indeed, the caking problem seems to be aggravated with the linear alkyl sulfonates and sulfates. This is one of the reasons why they 3,424,690 Patented Jan. 28, 1969 have not heretofore been commercialized to the same extent as the branched-chain alkyl benzene sulfonates. (See the book by P. A. R. Puplett, Synthetic Detergents, published by Sidgwick and Jackson, London, 1957.) Thus, known anticaking additives, although regarded as being satisfactorily effective in branched-chain alkyl benzene sulfonates, are often, on the other hand, not quite so effective with the straight-chain materials. Conversely, the presently contemplated caking inhibitors, although eminently effective in linear alkyl sulfonate and in linear alkyl sulfate and alkyl sulfonate detergent compositions, are unexpectedly not so effective as the known inhibitors when incorporated in the branched-chain alkyl benzene sulfonates.

It has now been found that the caking tendencies of particulate solid linear alkyl sulfonate and alkyl sulfate detergent can be suppressed by intimately admixing therewith a small but effective proportion of an anticaking agent selected from the group consisting of sodium sulfosuccin'ate and potassium sulfosuccinate of the formula SOaM CH2CH COOM COOM wherein M represents either sodium or potassium alkali metal. The anticaking additive can be prepared by adding sodium bisulfite to an aqueous solution of the disodium salt or maleic acid. If desired, the sodium bisulfite can be formed in situ by adding sodium hydroxide and S0 to the maleic acid salt. In general a satisfactory amount of anticaking agent can range from about 2 to 25%, preferably 8 to 20%, by weight, based on alkyl sulfate or alkyl sulfonate detergent.

The nonsoap alkyl sulfonate or alkyl sulfate that can be used in practicing the present invention can be represented by the formula in which R and R are hydrocarbyl radicals, the sum of the carbon atoms in R and R ranging from 9 to 20 atoms; and X is a group that can be OSO Y, SO Y or CH OSO Y, Y being a salt-forming cation or metal that can be an alkali metal, such as lithium, sodium, and potassium; or ammonium.

These secondary alkyl sulfates or alkyl sulfonates are known compounds available commercially.

Thus, the compound having the group OSO Y, i.e., the alkyl sulfate, can be prepared in known fashion by sulfating a secondary alcohol or by adding sulfuric acid to straight-chain a-olefins or internal olefins, as shown, for example, in US. Patents Nos. 2,587,990 and 2,573,730, followed by neutralization. Alkyl sulfonates can be prepared by the sulfoxidation reaction of saturated aliphatic hydrocarbons, or by the sulfochlorination reaction of saturated aliphatic hydrocarbons followed by hydrolysis, and neutralization. Detergent materials containing the group --CH OSO Y can be prepared from olefins by the 0x0 reaction, followed by sulfation, and neutralization. However prepared, the detergent precursor material containing the SO H group or the OSO H group is neutralized, as indicated, with appropriate base material to give the finished detergent or surface active product. Preferred bases are the alkali metal hydroxides, such as sodium hydroxide, lithium hydroxide or potassium hydroxide; or ammonium hydroxide.

The invention is applicable to built detergent compositions, i.e., compositions containing the nonsoap synthetic detergent, particularly those containing the groups OSO Y and -SO Y as above defined, and an inorganic salt detergent builder, such as a sulfate, carbonate, silicate, borate, or condensed phosphate sodium salt.

3 4 Therefore, a more specific embodiment of the invention The anticaking agent of the present invention can be is the preparation of a particulate solid detergent composiincorporated into the detergent composition by adding tion consisting essentially of nonsoap linear alkyl sodium preformed sodium or potassium sulfosuccinate either to sulfate or sulfonate detergent having caking tendencies, the neutralizing basic solution or to the sulfonation mixan inorganic sodium salt detergent builder, and a small but ture prior to or during the neutralization step.

effective amount to suppress said caking tendencies of the 5 As hereinabove indicated, in addition to inorganic aforesaid sodium or potassium sulfosuccinate anticaking sodium sulfate detergent builder, other inorganic salt deagent. The proportions of nonsoap synthetic detergent tergent builders, such as the condensed phosphates, carcan range from about 5 to 95%, preferably to 40%, bonates, silicates, and borates, can be incorporated in the by weight, based on it and detergent builder; inorganic 10 detergent composition. These may be added to the neudetergent salt builder, from 5 to 95%, preferably 60 to tralized slurry prior to drying in accordance with the 90%, by weight, based on it and nonsoap detergent; and specifications desired in the ultimate or finished composianticaking agent from about 2 to 25%, preferably 8 to tion. The slurry thus built is then converted to the par- 20%, by weight, based on nonsoap synthetic detergent. ticulate solid form and size by a suitable drying operation The invention is particularly useful in connection with such as spray-drying or drum-drying. so-called heavy-duty detergent compositions or synthetics As stated, a particularly useful composition is one based for household use, especially adapted for washing cotton. on synthetic detergent, for example, sodium alkyl sulfate As is known these compositions consist essentially of the detergent, and a condensed phosphate ordinarily used in nonsoap synthetic detergent and a condensed phosphate conjunction with a synthetic surfactant to produce aheavysuch as tetrasodium pyrophosphate and/or sodium triduty detergent composition. The polyphosphates can be polyphosphate, usually in a weight ratio of phosphate to used in their commercially available anhydrous form, obsynthetic detergent ranging from less'than 1:1 to more tained by the high-temperature dehydration of the orthothan 3:1. Other inorganic salt detergent builders as well phosphatestripolyphosphates, from a mixture of dican be present to the extent that the total inorganic salt sodium orthophosphate and monoorthophosphate; tetrabuilder including the phosphate, to synthetic detergent sodium pyrophosphate, from disodium orthophosphate; weight ratio can be as high as 10: 1. Further, as is known and sodium polymeta-phosphates, from orthophosphate. in the art, special purpose additives, such as a bleach, The various condensed phosphates can be used singly or in perfume, foam booster, etc., may be present in the finished admixture. As is known in the detergent art, the proporcomposition, in a combined amount up to by weight tions of the various phosphates are frequently altered in of the finished composition. 30 practice to meet the manufacturers own specifications.

Accordingly, a particularly useful embodiment of the Generally good results are obtained when sodium triinvention is the preparation of a heavy-duty particulate polyphosphate is essentially the sole condensed phosphate, solid detergent composition, at least 70% by weight thereor is admixed with the other condensed phosphate, for

of consisting essentially of linear C C alkyl sulfonate or example, 80% tripolyphosphate and 20% pyrophosphate. sulfate organic detergent, an inorganic salt detergent In addition to the detergent builders, other ingredients builder in a weight ratio to organic detergent ranging from or fillers, in combined amounts up to about 30 weight per- 1:1 to 10:1, said inorganic salt detergent builders includcent of the final composition, can be incorporated. Exing a condensed sodium phosphate, such as tetra-sodium amples of optional ingredients are those customarily pyrophosphate and/or sodium tripolyphosphate, present present in heavy-duty detergent formulations. These inin a Weight ratio to the organic detergent ranging from elude in Weight amounts based on final composition, an

about 1:1 to 3:1. anticorrosion and stabilizing agent, such as sodium sili- The anticaking agent is incorporated in the detergent cate, wherein the SiO to Na O ratio can range from 1/2 composition in such fashion as to effect intimate and to 2/1 in proportion of, for example, 5%; an anti-rethorough admixture with, or uniform dispersion throughdeposition agent, such as carboxymethyl cellulose, proout, the other components of the detergent composition. portions of about 1 to 3% being cited as illustrative; a This can be accomplished by wet-mixing, such as by foam modifier, such as a monoor di-ethanolamide of a forming an aqueous dispersion or slurry comprising the fatty acid, such as lauric isopropanolamide, in proportions, anticaking additive and other components of the composifor example, of 5%; a chemical bleaching agent, such as tion, and then drying the dispersion. Another way of sodium perborate or sodium percarbonate, for example, effecting uniform dispersions of the caking inhibitor in an amount of 2 to 5%, optical whiteners, in amounts throughout the composition is to integrate its incorporaof the order 0.1 to 0.2%, such as the triazinyland aroyltion with the process of making the nonsoap detergent stilbenzene. by adding the inhibitor at the neutralization step. In the tabulated experiments below, the specified non- It is often the practice to leave all or a part of the unsoap detergent was subjected to the visual tackiness test. reacted acid material used in the sulfation and sulfonation Except where indicated, the test samples were in the form steps, admixed with the alkyl sulfonic acids or alkyl 5111- of unbuilt detergent compositions, i.e., the detergent fates, and to neutralize them together to form an aqueous formed substantially the Whole of the sample. According dispersion or slurry of organic detergent and inorganic to the test, the dried powder with or without anticaking sodium sulfate salt, the inorganic sulfate later serving as agent was placed in an uncovered jar and exposed to a builder in the finished detergent composition. The slurry room conditions of temperature and humidity, i.e., 21 C. is then dried as by spray-drying or drum-drying and reand 55% relative humidity, for 16 hours. The results are duced to the desired particle shape and size. summarized in the following table:

TABLE I Visual tackiness test (additives) Example Sample identification None 15% STS 1 15% ATA 2 1 Cid-C19 0x0 sulfates from l-olefins Sticky, but less than LAS. Same as none. Free flowing. 2. ow on oxo sulfates from internal Sticky, but less than Example 1 .do Do. 3 012- 0 3 oxo sulfates from l-olefins. Tacky and plastic Free flowing, granular. 4 City-C20 sec-alcohol sulfate solution, On drying on hot plate, product turns Same as none Dries faster, product is white and free 17.8?0 ictive, 0.8% oil, 14.4% brown and is sticky. flowing.

5 Ora- 62 sec-parafiin suliouate Flakes which stick to container do Free flowing powder. 6 ..do ..do Somewhat tacky but flowing solid.

1 15% by weight based on detergent active of sodium toluene sullonate. 4 This material could not be dried and then tested as the others due 2 15% by weight based on detergent active of sodium sulfosuccinate, to decomposition. Therefore, the antitackiness agent was observed as except for Example 6. an aid to drying rapidly without decomposition.

3 Commercial linear alkyl benzene sulfonate detergent. 5 Potassium suliosuccinate used in place of sodium sullosuceinate.

The straight chain l-olefins used to make the detergent actives noted in Table I were commercially available mixtures derived from paraffin wax by a cracking process. Such a process yields a nearly even distribution of olefins. Either broad mixtures within the detergent range, e.g., C -C may be used or in order to obtain special properties, narrower mixtures may be used. Thus the C C l-olefins which were subjected to the oxo reaction in known manner to give G -C oxo sulfates were comprised of about l5:3% of each of the olefins from C through C along with minor amounts of C and C Fractionation of this olefin mixture, for instance by distillation at reduced pressure, in order to split it in half, gives as the lower boiling portion the C15-C17 and half of the C olefins. This mixture was also subjected to the oxo reaction to give the C C -0xo sulfates.

The internal olefins required for preparation of secondary alkyl sulfates or 0x0 sulfates may be obtained by dehydrogenation of paraflins using a two step method of chlorination followed by dehydrochlorination. Alternatively, the internal olefins may be made by isomerizing l-olefins by known processes.

In order to obtain high quality, i.e., straight chain parafiins to insure maximum biodegradability of the product, paraffins from petroleum sources must be treated to remove branched impurities. This may be done by several known processes, of which urea clathration and molecular sieve treatment are the most widely known. The thus purified paraffins may be used for sulfoxidation or sulfochlorination to produce secondary parafiin sulfonates.

The results of Table I indicate that sodium sulfosuccinate has the desirable feature of expediting the rate of drying as well as reducing the tackiness of the final product. This is a particularly useful property for use with temperature sensitive materials such as secondary alkyl sulfates and mixtures containing relatively large amounts of detergent and accompanied only by sodium sulfate, for example, 40% to 90% detergent active and the balance sodium sulfate and water. The use of sodium sulfosuccinate will be especially efficacious for drum drying of such mixtures, wherein the mixtures are exposed to elevated temperatures for relatively long periods of time compared, for instance, to the times and temperatures involved in spray drying.

A suitable method for determining the extent of caking in a built detergent composition, and the one utilized in the examples below, is the lift-tackiness test.

According to this test, the ingredients of the composition to be tested are formed into a water slurry of approximately 50% solids content. This slurry is mixed with a mechanical stirrer for 15 minutes and then dried on a glass plate. The glass plate is kept on a steam plate or hot plate which is kept at constant temperature in the range of 135150 C. The slurry is spread on with a large 31-mil doctor blade and allowed to dry until the dried product is readily scraped off (2 to 4 minutes). The composition then contains about 12% moisture. In order to simulate commercial spray dried products which ordinarily contain about moisture, the powders are left exposed to ambient conditions for 24 hours. This period of time is sufficient to allow them to attain the equilibrium moisture content. The ability to retain a high moisture content without exhibiting appreciable caking tendency is desirable; an additive which will reduce caking tendency while permitting more moisture to be left in the dried formulation is highly desirable.

The powder is then screened and that passing through a 20 mesh screen and retained on a 48 mesh screen is used for testing.

The apparatus used in the test comprises a stationary aluminum cylinder having a diameter of 1%", mounted above a spring pan balance supported on a screw-type jack. The bottom of the aluminum cylinder is covered with double-sided adhesive tape, which is changed with each test. The underside of the adhesive tape is coated with a thin layer of the test sample.

30 ml. of screened sample prepared as above is weighed, and is poured in the form of a conical pile on a piece of filter paper in a Petri dish having a diameter of 9 cm., and supported on the pan of the balance. The top of the sample pile is spread level to the top of the Petri dish.

The jack is slowly raised and the test sample is made to impinge upon the treated bottom of the aluminum cylinder to a pressure of g.

This pressure is maintained for 30 seconds, and then slowly released by lowering the jack. As soon as the Petri dish clears the sample adhering to the cylinder, a piece of stiff weighing paper is slid under the cylinder to catch any sample falling off the cylinder while the Petri dish is being lowered out of the way.

The powder adhering to the cylinder is scraped onto the same weighing paper, and the total amount of sample that has been lifted is weighed.

Caking tendency as measured by this test is rated on the volume of solids sticking to the plunger, calculated as follows, the lower the value, the less pronounced is the caking tendency:

wt. lifted 30 wt. of sample used EXAMPLE 7 (a) A detergent formulation having the following composition in parts by weight was prepared:

Taokiness (ml.)

Parts Sodium C C secondary alkyl sulfate (obtained by sulfation of C C a-olefins) 25 Sodium tripolyphosphate 40 Sodium silicate 7 Carboxymethyl cellulose 1 Sodium sulfate 19 EXAMPLE 8 (a) A detergent formulation having the following composition in parts by weight was prepared:

Parts Sodium C C secondary alkyl sulfonate 25 Sodium tripolypho-sphate 40 Sodium silicate 7 Carboxymethyl cellulose 1 Sodium sulfate 19 This composition had a tackiness of 6.3 ml. and an equilibrium moisture content of 7.5%.

(b) A composition was prepared as in 8(a), except that 3 parts sodium sulfate were replaced with 3 parts sodium sulfosuccinate. The composition had a moisture content of 8.4% and tackiness value of 4.2 ml.

In addition to the reduction in tackiness, it was also noticed in Examples 7 and 8 that each formulation containing the sodium sulfosuccinate, Examples 7b and 8b, dried more rapidly and showed no sign of decomposition, while the formulations containing no anticaking agent, Examples 7a and 8a showed varying degrees of decomposition on drying, as judged by color formulation.

I claim:

1. Process for suppressing the caking tendencies of a nonsoap detergent having caking tendencies, said nonsoap detergent being represented by the formula:

wherein R and R are essentially straight chain alkyl groups having a total of 9 to 20 carbon atoms, and X is OSO Y, SO Y or CH SO Y, wherein Y is an alkali metal or ammonium, which comprises uniformly dispersing throughout said detergent a small but effective amount substantially to suppress said caking tendencies of sodium sulfosuccinate or potassium sulfosuccinate.

2. Process according to claim 1, wherein the anticaking agent is present in an amount of 2 to 25%, by weight, based on nonsoap detergent.

3. Process according to claim 2, wherein the anticaking agent is present in an amount of about 8 to 20%, by weight, based on nonsoap detergent.

4. Process according to claim 2, wherein the anticaking agent is sodium sulfosuccinate.

5. Process according to claim 2, wherein the anticaking agent is potassium sul-fosuccinate.

6. A- built particulate solid detergent composition consisting essentially of straight-chain alkali metal or ammonium secondary alkyl sulfate or secondary alkyl sulfonate, in which the alkyl radical contains from 9 to 20 carbon atoms, as the nonsoap detergent component; inorganic sodium salt detergent builder component; and, as an anticaking agent component, sodium sulfosuccinate or potassium sulfosuccinate, the nonsoap detergent and the detergent builder each being present in a proportion within about the range of to 95%, by weight, based on the two, and the anticaking agent, in the range of about 2 to 25 by weight, based on the nonsoap detergent, said composition being obtained by drying an aqueous dispersion of the aforementioned components.

7. A built detergent according to claim 6, wherein the nonsoap detergent is present in a proportion in about the range of 10 to 40%, and the inorganic sodium salt detergent builder, in about the range 60 to 90%.

8. A built detergent according to claim 6, wherein the anticaking agent is present in an amount of about 8 to by weight, based on nonsoap detergent.

9. A built detergent composition according to claim 7, wherein the anticaking agent is sodium sulfosuccinate.

10. A built detergent composition according to claim 7, wherein the anticaking agent is potassium sulfosuccinate.

11. Heavy-duty particulate solid detergent composition at least about by weight thereof consisting essentially of a mixture of (a) nonsoap detergent represented by the formula:

7 wherein R and R are essentially straight chain alkyl radicals having a total of 9 to 20' carbon atoms, and X is either OSO Y or SO Y, wherein Y is an alkali metal or ammonium; and (b) inorganic sodium salt detergent builder, the weight ratio of inorganic sodium salt detergent builder to nonsoap synthetic detergent ranging from 1:1 to 10:1, and uniformly dispersed throughout the particles of said composition, as an anticaking agent, sodium s-ulfosuccinate or potassium sulfosuccinate, said anticaking agent being present in an amount ranging from about 2 to 25 by weight, based on nonsoap detergent.

12. Composition according to claim 11, wherein the anticaking agent is present in an amount of about 8-20%, by weight, based on the nonsoap synthetic detergent,

13. Composition according to claim 11, wherein the anticaking agent is sodium sulfosuccinate,

14. Composition according to claim 11, wherein the anticaking agent is potassium sulfosuccinate.

References Cited UNITED STATES PATENTS 2,181,087 11/1939 Caryl et a1. 252-161 2,702,818 2/1955 Jaquay 252161 X 2,717,243 9/1955 Bloch 252-384 X 2,969,332" 1/1961 Lawler et al. 252161 X LEON D. ROSDOL, Primary Examiner.

S. D. SCHWARTZ, Assistant Examiner.

US. Cl. X.R. 

